Official Solution:
Is the average (arithmetic mean) of data set S greater than its median? (1) Data set S consist of consecutive multiples of 3.
Data set S is evenly spaced. One of the most important properties of an evenly spaced set (also known as an arithmetic progression) is:
in any evenly spaced set, the arithmetic mean (average) is equal to the median. Therefore, the mean of \(S\) = the median of \(S\). This statement is sufficient.
(2) The sum of all terms of data set S is 75.
If \(S=\{75\}\), then the mean = median. However, if \(S=\{-1, 1, 75\}\), then the mean (25) is greater than the median (1). This statement is not sufficient.
Answer: A